Referring to FIG. 15, the conventional shelf (50) comprises a plurality of supporting posts (51) and a plurality of shelf boards (52), and each of the supporting posts (51) has a plurality of peripheral grooves (511) sequentially formed on a post body thereof. A plurality of locating members (53) is configured to dispose on the post body of the supporting post (51), and each of the locating members (53) comprises two arc panels which are configured to fit together to form a tapered-drum shape. Each of the locating members (53) has an engaging rib (531) protruding from an inner edge thereof. The shelf board (52) is made of metal bars through welding, and each of four corners of the shelf board (52) is connected with a connecting tube (521) through welding. A user can secure corresponding locating members (53) on the supporting posts (51) at a same height, and each of the engaging ribs (531) of the locating member (53) is configured to engage with the peripheral groove (511). Moreover, the connecting tubes (521) of the single shelf board (52) are configured to firmly couple with the locating members (53) at the same height thereby enabling the shelf board (52) to be supported by the supporting posts (51).
However, the conventional shelf is disadvantageous because: (i) the shelf board (52) is secured between the supporting posts (51) through connecting the connecting tubes (521) with the locating members (53) at the same height. In this way, each of the connecting tubes (521) has to firmly couple with the locating member (53) to steady the shelf board. As a result, after assembly, the locating members (53) cannot be moved freely and the shelf (50) has limitations when needing to add more shelf boards (52) thereon according to use conditions; and (ii) after assembly, a user cannot directly assemble additional shelf boards (52) without more supporting posts, which is inconvenient to use. Therefore, there remains a need for a new and improved design for a shelf to overcome the problems presented above.